Мъка

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace VendingMachine
{
    class Program
    {
        static void Main()
        {
            decimal coinsTotal = 0m;

            while (true)
            {
                string start = Console.ReadLine().ToLower();

                if (start == "start")
                {
                    break;
                }
                decimal coins = decimal.Parse(start);
                if (coins == 0.1m || coins == 0.2m || coins == 0.5m || coins == 1m || coins == 2m)
                {
                    coinsTotal += coins;
                }
                else
                {
                    Console.WriteLine($"Cannot accept {coins}");
                }

            }
            decimal nuts = 2.0m;
            decimal water = 0.7m;
            decimal crisps = 1.5m;
            decimal soda = 0.8m;
            decimal coke = 1.0m;

            while (true)
            {
                string product = Console.ReadLine().ToLower();

                if (product == "end")
                {
                    break;
                }

                if (product == "nuts")
                {
                    if (coinsTotal < nuts)
                    {
                        Console.WriteLine("Sorry, not enough money");
                    }
                    else
                    {
                        Console.WriteLine("Purchased nuts");
                        coinsTotal = coinsTotal - nuts;
                    }
                }
                else if (product == "water")
                {
                    if (coinsTotal < water)
                    {
                        Console.WriteLine("Sorry, not enough money");
                    }
                    else
                    {
                        Console.WriteLine("Purchased water");
                        coinsTotal = coinsTotal - water;
                    }
                }
                else if (product == "crisps")
                {
                    if (coinsTotal < crisps)
                    {
                        Console.WriteLine("Sorry, not enough money");
                    }
                    else
                    {
                        Console.WriteLine("Purchased crisps");
                        coinsTotal = coinsTotal - crisps;
                    }
                }
                else if (product == "soda")
                {
                    if (coinsTotal < soda)
                    {
                        Console.WriteLine("Sorry, not enough money");
                    }
                    else
                    {
                        Console.WriteLine("Purchased soda");
                        coinsTotal = coinsTotal - soda;
                    }
                }
                else if (product == "coke")
                {
                    if (coinsTotal < coke)
                    {
                        Console.WriteLine("Sorry, not enough money");
                    }
                    else
                    {
                        Console.WriteLine("Purchased coke");
                        coinsTotal = coinsTotal - coke;
                    }
                }
                else
                {
                    Console.WriteLine("Invalid product");
                }


            }
            Console.WriteLine($"Change: {coinsTotal:f2}");
        }
    }
}